Background: POCUS has become a powerful tool in the evaluation of critically ill patients in the ED. However, in patients with cardiac arrest, the use of POCUS has been shown to significantly increase the duration of pauses. This is concerning as high quality CPR with minimal interruptions is one of the keys to maximizing ROSC and survival with good neurologic outcomes. Recently, I had the chance to interview the lead author of the Cardiac Arrest Sonographic Assessment (CASA Exam) on REBEL Cast Ep 57 and on that episode we discussed a follow up study, which has finally been published in Resuscitation 2018.

What They Did: Quasi-experimental pre- and post-intervention study at a single institution ED to assess whether implementation of the CASA protocol reduces duration of interruptions in CPR during resuscitation of cardiac arrest patients

Proportion of pulse checks with ultrasound use increased form 65% pre-intervention to 80% post-intervention

ROSC

Pre-Intervention: 34%

Post-Intervention: 43%

P = 0.2

Survival to Hospitalization:

Pre-Intervention: 29%

Post-Intervention: 36%

P = 0.3

Survival to Discharge with CPC Score of 1 – 2:

Pre-Intervention: 6.3%

Post-Intervention: 5.2%

P = ?? (Not listed in the manuscript)

Strengths:

Cardiac arrest resuscitations were filmed and analyzed with respect to pause check duration and use of POCUS

Codes recorded 24hours a day, 7 days a week

Patients in both time periods were similar demographically and with respect to comorbidities

Limitations:

This is a pre- and Post-intervention study not a randomized clinical trial, which could result in residual confounding

Study was unblinded, therefore it is not possible to know what proportion of the findings were related to Hawthorne effect

Unable to correlate POCUS video clips to CPR pulse checks (i.e. there was no way to ensure residents were performing the protocol in the order it was intended to be done in)

Discussion:

Breakdown of the proportion of CPR pauses pre- and post-implementation of the CASA exam

Important to realize that decrease in pause duration could be due to Hawthorne Effect (participants performed better because they were aware that they were being evaluated and not because of the intervention itself)

Author Conclusion:“In this pre and post-intervention study, the implementation of a structured algorithm for ultrasound use during cardiac arrest significantly reduced the duration of CPR interruptions when ultrasound was performed.”

Clinical Take Home Point: Having a scripted protocol for POCUS in cardiac arrest, and placing the probe on the chest during compressions are associated with shorter duration of CPR pulse checks, but even with the CASA exam, CPR pulse checks are still longer than without the use of POCUS. Having a dedicated counter can ensure that pauses with POCUS do not last longer than 10 seconds.